1. Field of the Invention
The present invention relates to an endoscope gas feed system, an endoscope and an endoscope system. More particularly, the invention relates to an endoscope gas feed system, an endoscope and an endoscope system in which intraluminal observations and treatments are performed by supplying a constant-pressure gas from a gas feed unit into a lumen of a subject being tested through an opening provided at a distal end portion of a flexible endoscope inserted into the lumen.
2. Description of the Related Art
Conventionally, medical diagnostics using an endoscope has been widely practiced in the field of medicine. In particular, an image pickup element, such as a CCD, is built into a distal end portion of an endoscope to be inserted into a body cavity to take an image of the interior of the body cavity, and signal processing is performed using a processor unit to display the image on a monitor, so that a doctor observes and uses this image for diagnosis or inserts a treatment instrument from a treatment instrument insertion channel to perform treatments, such as sample collection and polyp removal.
In particular, when an insertion part of a flexible endoscope having flexibility is inserted into a lumen, such as a stomach or a large intestine, to perform intraluminal diagnoses or treatments, a treatment instrument is inserted into a lumen through a forceps channel (treatment instrument channel) of the flexible endoscope to perform curative treatments therein.
At this time, a constant-pressure feed gas, such as a carbon dioxide gas, is supplied into the lumen to expand the lumen, in order to secure the visual field of the flexible endoscope and a space for operating treatment instruments.
For example, Japanese Patent Application Laid-Open No. 2009-106360 discloses a laparoscopic surgery system in which a plurality of trocars is punctured into the abdomen of a patient, a rigid endoscope is inserted into an abdominal cavity from one of the trocars, and a pneumoperitoneum gas supplied from a pneumoperitoneum unit is introduced into the abdominal cavity through another trocar. In addition, a flexible endoscope is inserted into a lumen, such as a large intestine and, thus, these two endoscopes are used in the system. In this system, a carbon dioxide gas is introduced as a pneumoperitoneum gas from the pneumoperitoneum unit into the abdominal cavity through the another trocar in a state of being regulated to a predetermined pressure, so that the carbon dioxide gas is supplied into the lumen through the treatment instrument channel of the flexible endoscope.
In addition, Japanese Patent Application Laid-Open No. 2007-296164, for example, discloses a system in which a gas for securing the visual field of an observation window and a pneumoperitoneum gas are sprayed from a spray nozzle provided at the leading rigid portion of the insertion part of an endoscope. Particularly in order to reduce an operator's frequency of operating a gas/water feed valve used to clean the observation window so as to remove contaminants attached thereto, a carbon dioxide gas is automatically sprayed from the spray nozzle along surfaces of the observation window, thereby forming a fluid curtain thereon.
Yet additionally, Japanese Patent Application Laid-Open No. 2005-176908, for example, discloses a system equipped with a pneumoperitoneum gas circulation mechanism in which distal end openings of the starting end-side and terminal end-side flow paths of a fluid curtain are disposed in upper and lower positions across an observation window disposed on the distal end surface of an endoscope, so as to be substantially in alignment with the observation window, thereby supplying and exhausting a pneumoperitoneum gas within an abdominal cavity to circulate the gas.
However, if a constant-pressure gas supply is provided through an opening of the treatment instrument channel, such as a forceps port, formed on the distal end portion of the flexible endoscope, as in the system described in, for example, Japanese Patent Application Laid-Open No. 2009-106360 mentioned above, bubbles are generated near a gas spray port by bodily fluids and water attached to the distal end surface of the endoscope. Thus, the system has had the problem that those bubbles attach to an observation window (image pickup unit) formed on the distal end surface of the endoscope and interrupt the visual field of the observation window.
In the systems described in Japanese Patent Application Laid-Open Nos. 2007-296164 and 2005-176908, a fluid curtain is formed on the distal end surface in which the observation window is formed to remove contaminants attached thereto. However, none of these systems are configured to provide a constant-pressure supply of a pneumoperitoneum gas from the distal end surface of the flexible endoscope. The endoscope used is a rigid endoscope and the pneumoperitoneum gas is supplied into an abdominal cavity through a trocar. In particular, the system described in Japanese Patent Application Laid-Open No. 2005-176908 removes contaminants splashed on the observation window by the flow of a circulating pneumoperitoneum gas formed on a surface of the observation window. In addition, the system suppresses variations in a gas pressure within the abdominal cavity by circulating the gas while achieving a pressure balance between discharge at the distal end opening of the starting end-side flow path of the fluid curtain and suction at the distal end opening of the terminal end-side flow path of the fluid curtain.
As described above, the systems described in Japanese Patent Application Laid-Open Nos. 2007-296164 and 2005-176908 are not configured to provide a constant-pressure supply of a pneumoperitoneum gas from the distal end surface. Thus, no consideration has been given to the problem that the visual field of the observation window is interrupted by bubbles generated at the distal end surface.